which of these statements describes the United States at the time of Missouri's request for statehood

The correct answer is:

The balance between free and slave states was equal

The Missouri Compromise was the legislation that provided for the admission of Maine to the United States as a free state along with Missouri as a slave state, thus maintaining the balance of power between North and South in the United States Senate. Equalizing the number of free and slave states in the U. S.

"The Senate gave each state two votes. And by convention since the signing of the Constitution, the Senate was evenly divided between slave states and non-slave states. So the admission of Missouri would have added a slave state to the Senate and left the northern non-slave states as a minority. And they were not going to accept this."